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Give aging technology a chance

Think twice before throwing out your old tech. Perhaps that disused piece of junk can have a second chance in your next DIY project.

Let’s rewind the clock to 2001: NASA lands the first spacecraft on an asteroid, Gladiator wins the Academy Award for best picture, and Handspring releases the Handspring Visor Neo, the company’s affordable PDA competitor of the Palm Pilot. At the time, this baby was screaming (for hand-helds) with a 33MHz processor, 8MB of RAM and a high resolution 160×160 pixel gray-scale display. The following year, I was lucky enough to get this high-tech piece of portable technology as a barter deal for helping a neighbour understand how to use their own PDA.

I kept my Visor in working order over the years and it was still limping along when smartphones became affordable and I didn’t need it any more. After it was clear that my old friend was no longer useful as a practical tool, I looked into selling it on eBay, but found more equivalent devices that went unsold than sold so I had the choice of either throwing it out or trying to find something else to do with it. Since I’m not inclined to ‘e-waste’, I started digging around for potential ways I could repurpose it on the internet. Handspring made it’s niche in the PDA market with their springboard expansion slot, so I was really interested in figuring out how to hack it (the device has a docking interface and an IR transceiver, too). Given its age, I had a LOT of broken links to sort through, but I eventually found NS Basic Palm, Pocket C palm, Palmphi, and Palm OS Emulator. It took a while, but I was finally able to hijack the emulator from POSE and use a ROM that I found online to use for exploring the potential of the programming languages on the go. I found out that Handspring once had a development kit for the springboard expansion slot, but was disappointed to find that it was no longer available from Palm.

While I was excited at the prospect of writing apps for a new platform, I realized that there was no way I’d be carrying the Visor around with me on a daily basis, so aside from can-I-do-it curiosity, the Visor was doomed to be recycled. The turning point was when I discovered that the Handspring PDAs (and I suspect other Palm Pilots as well) used serial protocols to sync data with the PC. If you look at the circuit board inside the serial docking station, the connection is direct from PDA to PC. I suspect that the only addition the USB docking station brings is an FTDI. The most exciting discovery was that Pocket C had a couple functions allowing the Visor to establish the serial connection and push data independent of syncing. I suppose I should have figured that this was possible since the Targus Stowaway keyboard connected through the docking port. This was such a revelation: If serial comms was possible, then I could connect this little computer to anything with a serial port… The possibilities were endless.

A few wires and a Molex connector were all I needed to tap into the serial connections on the cradle

I decided that the best thing I could do was to relieve my computer of the burden of driving my Lynxmotion robot arm. Since the development software I had didn’t include objects like buttons and sliders, I created my own. Using basic drawing features like boxes, lines, and text, I was able to create a GUI with buttons, indicators, and a slider so I could engage the serial port and individually control each servo in the robot. In the process of developing my program, I realized that I needed a controller that could read data from sensors if I wanted the arm to do anything useful, so as it turns out the Visor wasn’t a good fit for the robot arm in the long-term, but the device had proven itself. Who knows what else I might be able to use it for in the future? Maybe it’s going to be my next universal remote control? I still haven’t figured out how to dig into the springboard expansion slot, but I suspect that it’s going to unlock an even bigger potential for my little friend. Perhaps the next step is to reverse engineer the GPS expansion I bought years ago, but could never get to work.

My standalone robot arm with it’s new(ish) computer brain

The big lesson I learned here was your next project doesn’t have to start as $100+ in new electronics, maybe it starts with that old gadget you have laying around with lots of hidden potential.

Thanks for the question Gregg. The pinout on the port is very straightforward. You can find an explanation of each pin at http://pinouts.ru/PortableDevices/visor_pda_pinout.shtml. This website has proven to be a very handy resource for all kinds of pinouts.
I don’t presume to be an expert on the handspring docking cradle, but using a multimeter, you should be able to determine where you can land your solder connections. The picture I posted should be helpful, too.

Thanks, Kralimah,
I don’t know anything about the HPx2790b, but if you want to use it in a similar fashion to my project, I would find it’s data port, see if you can find the pinout online, then find some form of C or Basic that can compile to Windows CE5.0 so you can communicate through the data port.
Good Luck and let me know how your project goes!